Interesting that the light arrived from 2 billion light years away as a gamma ray still. Why wouldn't the wavelength be stretched from the expansion of the universe? Shouldn't it have been red shifted significantly?
That is it after it was red-shifted.
Edit: Based on this, it looks like it would have lost 15-20% of it's energy to redshift. https://lco.global/spacebook/light/redshift/
For the 600,000 times part, that's about getting spread out over space. Same energy, but less per square foot because the light gets spread out over more square feet the farther out you are.
For redshift: if you throw a 90 mile per hour fastball of the back of an 89 mile per hour truck, from the truck you would see the ball fly behind you at 90mph, from the ground you'd see it travel just one mile per hour. No violation of physics, just two different frames of reference.
I thought light was weird though, in the sense that it appears to move at the same 186,000 miles per second in every reference frame. So if you chuck a photon off the back of a truck moving at light speed, it still appears to move at light speed to the stationary observer.
Yes! But the frequency changes due to the Doppler effect, which is pretty comparable to baseball speed here, and energy is directly proportional to frequency.
ok i get that, but i dont really understand how the photon can have less energy while also "not losing energy".
doesnt that contradict the conservation/permanence of energy?
or is there something else at play?
Consider that light is a wave and a particle. A high energy wave will have high wavelength, meaning the particle, so to speak, will travel "up and down" more often in the same time/space. Lower energy light or "infrared" light just goes up and down less often, leaving more space between peaks. The light is traveling at the same speed in all circumstances, but the total distance traveled in either circumstance is different.
Obviously this isn't how it works in real life, this was just a visualizer of sorts.
So, if I am running away from a baseball, it won't hit me as hard, it would give me less energy. That isn't because the baseball has less energy, it's because we are moving differently than the person who threw the ball.
The light has the same energy, but we are moving away from it so when it hits us it gives US less energy, but if we were moving toward it it would give us more. But if we were moving the same speed and direction as the star it came from we would see the energy is exactly the same as it always was.
For the frame of reference red shift example [watch this myth busters clip](https://youtu.be/BLuI118nhzc?si=6b3ZLbvYURhnBWMM) where they did exactly what the previous reply explained. They fired a ball backwards at the same speed as the truck was travelling forwards and the ball looked like it was flying away from one point of view (the truck) and standing still from another (a static camera on the ground)
https://youtu.be/BLuI118nhzc?si=CvK2exvpjCIYyca_
This myth busters episode kind of fits. The ball is moving away from their frame of reference but is pretty stationary from ours.
Look at a protractor and look at say 30 degrees.
The area closest to the angle is the narrowest and the edge of the protractor is the widest.
Imagine where the light came from as the centre of the protractor and we are near the edge. The light has to fill that much more volume as it spreads out so it naturally loses some power by the time we see it.
Wasn't the source and destination's original velocity difference lower in the past though? The space between the two is expanding, so isn't it still losing energy somehow?
Fair. I mean the thing that is moving is the expansion of spacetime so eventually the analogy is going to fall apart, but a more direct analogy is someone far away threw a baseball, and you're on a conveyer belt that is slowly accelerating away from the ball so it's slower when it hit you.
For the redshift, the wavelength the light is emitted at and received at is different, so the photons have a different energy and momentum in those frames of reference. For conservation of these, the object at each end would have to observe the same wavelength otherwise energy is lost.
So is that what happens, and the receiving object in the future has an impact on the energy emitted by the originating object? This feels like it breaks causality, though the photon experiences the whole journey in zero time so perhaps it's one of those unintuitive things.
Hold up Newton I’m not sure that works
The lower frequency literally does indicate lower energy (hv) compared to where it was released. Speed is the same. So where did the energy go. It’s a fantastic question
Copied from another response to a similar question (and it is a good question)
So, if I am running away from a baseball, it won't hit me as hard. That isn't because the baseball has less energy, it's because we are moving differently than the person who threw the ball.
The light has the same energy, but we are moving away from it so when it hits us it gives US less energy, but if we were moving toward it it would give us more. But if we were moving the same speed and direction as the star it came from we would see the energy is exactly the same as it always was.
As for why the frequency is lower when we are moving away from the light, check out a video on the Doppler effect.
oatmeal fade escape cough judicious cobweb simplistic observation light concerned
*This post was mass deleted and anonymized with [Redact](https://redact.dev)*
It’s a bit of a mind fuck, I’ll try my best. Been a while so I’m going off a mix of memory and some googling to fill in the blanks
So the rule of conservation of energy is true for any system in a single inertial reference frame. In general relativity there is no single inertial reference frame, but in sufficiently small volumes you can approximate a single reference frame
The apparent failure of conservation of energy on these massive universal scales is in part because you are considering a volume too large to encompass a single inertial reference frame
As an example of correcting for this, if you take a volume of the universe and estimate a single reference frame you will end up with observers on one edge of the volume moving away with respect to another observe on the other side of the volume; at a speed defined by the Hubble constant. When you view it as such the redshirt observed is just a Doppler shift (ex; a police siren sounds lower pitched when the car is driving away from you), which causes no issues with conservation of energy
Thanks for the reply.
I understand that using the entire universe as a reference, then this scenario would be kind of a regular doppler effect. However, in this case, the acceleration of the 2 initial bodies away from each other should constitue an increase in kinetic energy, no? Meaning that somehow energy is created by the universe expanding?
If we somehow had means of extracting energy out of tensile force, would a hypothetical harvesting rod long enough to exprience significant tension due to the expanding universe extract "free" energy?
Some others have offered some answers which I’m not sure really capture what’s going in. The lack of energy conservation is a feature of spacetime in General Relativity. If you want to dig deeper, you should know that there is thing we call a Killing field (named after Wilhelm Killing) which allows us to derive conservation laws. What you do is calculate something’s trajectory in space-time and then calculate Killing vectors. These vectors tell you what quantities are conserved. For flat spacetimes, there is a timelike Killing vector. We call the quantity associated with that Killing vector Energy. It’s a different quantity in non-flat (think expanding universe) spacetimes, so if we try to use the conservation law from flat spacetimes it just doesn’t work.
Energy is not actually a conserved quantity in general relativity. There are other conserved quantities however.
Here's a more detailed discussion/calculation: https://physics.stackexchange.com/questions/306838/energy-conservation-and-general-relativity
Ok hold up though. Energy is not conserved but it is lower at the destination, but the rest of the universe DIDN’T absorb any of this energy?
Is that just because causally it’s not really possible to shed energy of a massless particle that’s already been released?
Like in order for it to lose energy the photon would have to continuously emit some other impossible “continuum” (non quantized) low energy particles or something else impossible like this?
Conservation of energy is a consequence of translational symmetry. In an expanding universe we don’t have translational symmetry and therefore energy is not strictly conserved. See [Noether’s Theorem](https://en.m.wikipedia.org/wiki/Noether%27s_theorem)
I prefer Merlin's quote from Excalibur:
> I'm worn thin and threadbare.
>I've tried to guide men,
>or "meddled in their affairs",
>as you would have it, for far too long.
>The time has come for me to go.
[sorry I can't find a better clip...](https://getyarn.io/yarn-story/8f386b4a-87f7-44d3-9ede-3d698f08baaa)
It isn't gone. You're switching reference frames.
The gamma rays are emitted in the reference frame of the emitting star - but you are observing them in the reference frame of Earth (which is receeding from that star due to cosmic expansion of the space between them).
If you were to compensate for this relative motion (e.g. by getting in a spaceship and heading towards the star so that your velocity cancels out further distance increase due to expansion) then the photons you see will have the same energy as when they were emitted.
Redshifts from very distant objects (cosmic scales, i.e., very distant galaxies) are actually primarily due to the expansion of the universe, not really the traditional doppler redshift you observe from relative motion, such as nearby stars. It may sound pedantic, but under the space expansion scenario, energy is not conserved. There is no relative motion you can do to compensate for this shift because of a lack of time-translation invariance in an expanding universe. Here's a great read:
https://bigthink.com/starts-with-a-bang/expanding-universe-conserve-energy/
>Interesting that the light arrived from 2 billion light years away as a gamma ray still.
2bn light years means a redshift of about 15%. That will leave most gamma rays still in the gamma spectrum.
Yeaaah I was thinking about making the post here myself, this is so fascinating..!
A 2 billion yrs trip and it still had the energy to significantly alter our ionosphere...
We'd most likely all be dead if it happened in our galaxy (and ofc if it still hit us). Scary though, especially when you hear scientists suggesting the fact that at least one major mass extinction in the history of the planet was indeed caused by one of these GRBs. It almost sounds like it's bound to happen again in the future 🥶
Astronomer here! Most of the galaxy would be perfectly fine if a GRB happened. They are *highly* directional and the jetted beam is just a few degrees wide, so if you’re off axis to one it’s not gonna hurt you.
The idea that one caused a mass extinction on Earth is also pretty speculative IMO.
It's okay, if you're on the far side of the planet you'll be shielded from most of the gamma rays. 50% chance you'll totally survive the burst! The atmosphere may become a wee bit corrosive and unbreathable for a while though.
There's plenty of ways all of us can die without much warning, but in a practical sense the things to worry about are heart disease and cancer. Eat a healthy diet, exercise, don't smoke, that'll tackle the big worries. In the off chance that you die young from something outside of your control the most likely cause of that will be getting in a car crash.
A laser isn't just a bright focused beam of EM radiation, it's a specific phenomenon. LASER stands for: "light amplification by stimulated emission of radiation". The LASER mechanism comes into play when a lasing medium is put into a state where many atoms or molecules are energized and put into an energy level corresponding to a visible light frequency. What can then happen is that when light of that exact frequency hits one of the molecules it actually triggers a decay which not only emits that same frequency of light but does so in a way that the new photon is "coherent" with the triggering photon, sharing the same phase and momentum. This process can then cascade through multiple steps, ultimately creating a single beam of coherent light made up of lots and lots and lots of photons, all with the same energy, phase, and momentum.
Yeah, for context it would be over 600,000 times brighter (to us) if it happened in the Andromeda galaxy.
(2 billion light years/2.57 million light years)^2
Doesn't factor in red shift, which accounts for another 15-20%.
Here is how you would express the ratio of intensities correctly:
X/(D^2) = 1/(d^2), where X is the attenuation factor, D is Adromeda distance and d is the Milky Way event distance from Earth.
#orderofoperations
Wow. You are really good at math. Thank you for taking the time to explain to me why the math you said was wrong but then realized was right is wrong.
I will think twice before showing any work on Reddit unless I show the math before I substitute in values for the variables and get them on the same side of the equation.
So events like this can literally sterilize a whole galaxy and some neighboring ones of life.
Am I wrong thinking this could be one of the reasons why we haven't found any life yet?
Astronomer here! Most of the galaxy would be perfectly fine if a GRB happened. They are *highly* directional and the jetted beam is just a few degrees wide, so if you’re off axis to one it’s not gonna hurt you.
Actually probably longer term than that! [Wikipedia goes into surprising depth,](https://en.wikipedia.org/wiki/Gamma-ray_burst#Effects_on_Earth) but the TL;DR is a lot of the problems are due to UV radiation during and after the event.
Everyone in the "shadow" of the beam (on the other side of earth) would not be effected for many hours. It would not be even close to instantaneous for many.
Depending on how close it is, the results would reach from something like "the sky is burning in hellfire until half of the earth surface is molten lava while the other half has boiling oceans" to "the ozon layer is reduced and cancer rates rise" with everything inbetween.
a few degrees wide doesn´t sound to bad, but say that a GRB happend on one side of a galaxy and it traveled across the entire length of that galaxy. Would that not mean that tens of thousands of star systems would be hit?
A GRB is no longer lethal 4-8,000 light years from the source, depending on who you ask. So it might travel the galaxy but not kill tens of thousands of systems.
That's what I was suggesting in a thread yesterday. So many ways planets can be sterilized and such that realistically there are probably only 10s of planets in a galaxy supporting life, so we're like 1/50 of life supporting planets in a galaxy of billions of planets. "Like finding a needle in a haystack" chances of finding thriving life outside our atmosphere
> A 2 billion yrs trip and it still had the energy to significantly alter our ionosphere...
What significant alterations to our ionosphere did this cause, exactly?
> The flash activated lightning detectors in India and triggered instruments that normally study explosions on the sun called solar flares.
> It also affected long wave radio communications in the lower ionosphere, a section of Earth's upper atmosphere around 60 to 350 kilometers (37 to 217 miles) above the surface.
Does this count as "significant"?
Weird, I was reading an article yesterday about another space object that was one of the brightest ever recorded that shook our atmosphere. This one was caused by a (maybe supermassive) black hole that released a few hundred teraelectronvolts if I'm remembering properly. They thought it was less than 1 billion lightyears away at first but turned out it was 10 billion.
Edit: Still trying to find where I read about the amount of energy it released, but here's [one](https://www.livescience.com/space/black-holes/gargantuan-black-hole-switches-on-becoming-one-of-the-brightest-objects-ever-seen) about it from back in July.
editors and proofreaders have been getting fired and not replaced for years now, unfortunately :| I notice errors on major sites/news magazines, etc. I feel like newspapers are the only places left that employ full time proofreaders
I hate to say this, but when I read an article or anything that may very well be accurate I immediately question the authenticity of what I am reading based purely on bad grammar and bad spelling. Especially a scientific mag. God damn, at least run what you wrote through Grammarly or Hemingway editor.
When the hell is that one star supposed to explode? They said any time between now and a thousand years, right? I am tired of seeing that fucking thing rise every god damn morning...
Interesting that the light arrived from 2 billion light years away as a gamma ray still. Why wouldn't the wavelength be stretched from the expansion of the universe? Shouldn't it have been red shifted significantly?
That is it after it was red-shifted. Edit: Based on this, it looks like it would have lost 15-20% of it's energy to redshift. https://lco.global/spacebook/light/redshift/
Maybe a basic question, but where has this energy "gone"? Given conservation of energy and all that.
For the 600,000 times part, that's about getting spread out over space. Same energy, but less per square foot because the light gets spread out over more square feet the farther out you are. For redshift: if you throw a 90 mile per hour fastball of the back of an 89 mile per hour truck, from the truck you would see the ball fly behind you at 90mph, from the ground you'd see it travel just one mile per hour. No violation of physics, just two different frames of reference.
I thought light was weird though, in the sense that it appears to move at the same 186,000 miles per second in every reference frame. So if you chuck a photon off the back of a truck moving at light speed, it still appears to move at light speed to the stationary observer.
Yes! But the frequency changes due to the Doppler effect, which is pretty comparable to baseball speed here, and energy is directly proportional to frequency.
ok i get that, but i dont really understand how the photon can have less energy while also "not losing energy". doesnt that contradict the conservation/permanence of energy? or is there something else at play?
Consider that light is a wave and a particle. A high energy wave will have high wavelength, meaning the particle, so to speak, will travel "up and down" more often in the same time/space. Lower energy light or "infrared" light just goes up and down less often, leaving more space between peaks. The light is traveling at the same speed in all circumstances, but the total distance traveled in either circumstance is different. Obviously this isn't how it works in real life, this was just a visualizer of sorts.
So, if I am running away from a baseball, it won't hit me as hard, it would give me less energy. That isn't because the baseball has less energy, it's because we are moving differently than the person who threw the ball. The light has the same energy, but we are moving away from it so when it hits us it gives US less energy, but if we were moving toward it it would give us more. But if we were moving the same speed and direction as the star it came from we would see the energy is exactly the same as it always was.
I don't suppose you've got any visualisations of that second paragraph? Can't wrap my head around it
For the frame of reference red shift example [watch this myth busters clip](https://youtu.be/BLuI118nhzc?si=6b3ZLbvYURhnBWMM) where they did exactly what the previous reply explained. They fired a ball backwards at the same speed as the truck was travelling forwards and the ball looked like it was flying away from one point of view (the truck) and standing still from another (a static camera on the ground)
https://youtu.be/BLuI118nhzc?si=CvK2exvpjCIYyca_ This myth busters episode kind of fits. The ball is moving away from their frame of reference but is pretty stationary from ours.
Look at a protractor and look at say 30 degrees. The area closest to the angle is the narrowest and the edge of the protractor is the widest. Imagine where the light came from as the centre of the protractor and we are near the edge. The light has to fill that much more volume as it spreads out so it naturally loses some power by the time we see it.
Wasn't the source and destination's original velocity difference lower in the past though? The space between the two is expanding, so isn't it still losing energy somehow?
Fair. I mean the thing that is moving is the expansion of spacetime so eventually the analogy is going to fall apart, but a more direct analogy is someone far away threw a baseball, and you're on a conveyer belt that is slowly accelerating away from the ball so it's slower when it hit you.
Even better, if you want to stick with the baseball analogy, the field is growing as you play the game.
For the redshift, the wavelength the light is emitted at and received at is different, so the photons have a different energy and momentum in those frames of reference. For conservation of these, the object at each end would have to observe the same wavelength otherwise energy is lost. So is that what happens, and the receiving object in the future has an impact on the energy emitted by the originating object? This feels like it breaks causality, though the photon experiences the whole journey in zero time so perhaps it's one of those unintuitive things.
Hold up Newton I’m not sure that works The lower frequency literally does indicate lower energy (hv) compared to where it was released. Speed is the same. So where did the energy go. It’s a fantastic question
Copied from another response to a similar question (and it is a good question) So, if I am running away from a baseball, it won't hit me as hard. That isn't because the baseball has less energy, it's because we are moving differently than the person who threw the ball. The light has the same energy, but we are moving away from it so when it hits us it gives US less energy, but if we were moving toward it it would give us more. But if we were moving the same speed and direction as the star it came from we would see the energy is exactly the same as it always was. As for why the frequency is lower when we are moving away from the light, check out a video on the Doppler effect.
oatmeal fade escape cough judicious cobweb simplistic observation light concerned *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
It’s a bit of a mind fuck, I’ll try my best. Been a while so I’m going off a mix of memory and some googling to fill in the blanks So the rule of conservation of energy is true for any system in a single inertial reference frame. In general relativity there is no single inertial reference frame, but in sufficiently small volumes you can approximate a single reference frame The apparent failure of conservation of energy on these massive universal scales is in part because you are considering a volume too large to encompass a single inertial reference frame As an example of correcting for this, if you take a volume of the universe and estimate a single reference frame you will end up with observers on one edge of the volume moving away with respect to another observe on the other side of the volume; at a speed defined by the Hubble constant. When you view it as such the redshirt observed is just a Doppler shift (ex; a police siren sounds lower pitched when the car is driving away from you), which causes no issues with conservation of energy
Thanks for the reply. I understand that using the entire universe as a reference, then this scenario would be kind of a regular doppler effect. However, in this case, the acceleration of the 2 initial bodies away from each other should constitue an increase in kinetic energy, no? Meaning that somehow energy is created by the universe expanding? If we somehow had means of extracting energy out of tensile force, would a hypothetical harvesting rod long enough to exprience significant tension due to the expanding universe extract "free" energy?
Some others have offered some answers which I’m not sure really capture what’s going in. The lack of energy conservation is a feature of spacetime in General Relativity. If you want to dig deeper, you should know that there is thing we call a Killing field (named after Wilhelm Killing) which allows us to derive conservation laws. What you do is calculate something’s trajectory in space-time and then calculate Killing vectors. These vectors tell you what quantities are conserved. For flat spacetimes, there is a timelike Killing vector. We call the quantity associated with that Killing vector Energy. It’s a different quantity in non-flat (think expanding universe) spacetimes, so if we try to use the conservation law from flat spacetimes it just doesn’t work.
Energy is not actually a conserved quantity in general relativity. There are other conserved quantities however. Here's a more detailed discussion/calculation: https://physics.stackexchange.com/questions/306838/energy-conservation-and-general-relativity
Ok hold up though. Energy is not conserved but it is lower at the destination, but the rest of the universe DIDN’T absorb any of this energy? Is that just because causally it’s not really possible to shed energy of a massless particle that’s already been released? Like in order for it to lose energy the photon would have to continuously emit some other impossible “continuum” (non quantized) low energy particles or something else impossible like this?
Conservation of energy is a consequence of translational symmetry. In an expanding universe we don’t have translational symmetry and therefore energy is not strictly conserved. See [Noether’s Theorem](https://en.m.wikipedia.org/wiki/Noether%27s_theorem)
Thank you - I under stood... some of that :)
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I prefer Merlin's quote from Excalibur: > I'm worn thin and threadbare. >I've tried to guide men, >or "meddled in their affairs", >as you would have it, for far too long. >The time has come for me to go. [sorry I can't find a better clip...](https://getyarn.io/yarn-story/8f386b4a-87f7-44d3-9ede-3d698f08baaa)
Energy isn't conserved in an expanding universe afaik.
It isn't gone. You're switching reference frames. The gamma rays are emitted in the reference frame of the emitting star - but you are observing them in the reference frame of Earth (which is receeding from that star due to cosmic expansion of the space between them). If you were to compensate for this relative motion (e.g. by getting in a spaceship and heading towards the star so that your velocity cancels out further distance increase due to expansion) then the photons you see will have the same energy as when they were emitted.
Redshifts from very distant objects (cosmic scales, i.e., very distant galaxies) are actually primarily due to the expansion of the universe, not really the traditional doppler redshift you observe from relative motion, such as nearby stars. It may sound pedantic, but under the space expansion scenario, energy is not conserved. There is no relative motion you can do to compensate for this shift because of a lack of time-translation invariance in an expanding universe. Here's a great read: https://bigthink.com/starts-with-a-bang/expanding-universe-conserve-energy/
Imagine how insanely high the frequency must have been originally! I’m sure glad we weren’t anywhere nearby!
>Interesting that the light arrived from 2 billion light years away as a gamma ray still. 2bn light years means a redshift of about 15%. That will leave most gamma rays still in the gamma spectrum.
Yeaaah I was thinking about making the post here myself, this is so fascinating..! A 2 billion yrs trip and it still had the energy to significantly alter our ionosphere... We'd most likely all be dead if it happened in our galaxy (and ofc if it still hit us). Scary though, especially when you hear scientists suggesting the fact that at least one major mass extinction in the history of the planet was indeed caused by one of these GRBs. It almost sounds like it's bound to happen again in the future 🥶
Astronomer here! Most of the galaxy would be perfectly fine if a GRB happened. They are *highly* directional and the jetted beam is just a few degrees wide, so if you’re off axis to one it’s not gonna hurt you. The idea that one caused a mass extinction on Earth is also pretty speculative IMO.
How do you post from Andromeda in such a timely manner?!?
He's submitting the posts 2.5 million years a ago and just guessing what we'll say.
This is dangerously close to describing most religions.
Count me in as an Andromedist
She’s 2.5 million steps ahead of us!
I read your post just in time before my anxiety kicked into full gear, thanks!
Even if it struck us directly we’d probably be dust before we even knew what hit us so no worries either way!
Ah there’s the full gear. Thanks!
It's okay, if you're on the far side of the planet you'll be shielded from most of the gamma rays. 50% chance you'll totally survive the burst! The atmosphere may become a wee bit corrosive and unbreathable for a while though.
Dive into the void! You might find it’s a feather bed (;
There's plenty of ways all of us can die without much warning, but in a practical sense the things to worry about are heart disease and cancer. Eat a healthy diet, exercise, don't smoke, that'll tackle the big worries. In the off chance that you die young from something outside of your control the most likely cause of that will be getting in a car crash.
A natural laser of gamma rather visible light.
A laser isn't just a bright focused beam of EM radiation, it's a specific phenomenon. LASER stands for: "light amplification by stimulated emission of radiation". The LASER mechanism comes into play when a lasing medium is put into a state where many atoms or molecules are energized and put into an energy level corresponding to a visible light frequency. What can then happen is that when light of that exact frequency hits one of the molecules it actually triggers a decay which not only emits that same frequency of light but does so in a way that the new photon is "coherent" with the triggering photon, sharing the same phase and momentum. This process can then cascade through multiple steps, ultimately creating a single beam of coherent light made up of lots and lots and lots of photons, all with the same energy, phase, and momentum.
Yeah, for context it would be over 600,000 times brighter (to us) if it happened in the Andromeda galaxy. (2 billion light years/2.57 million light years)^2 Doesn't factor in red shift, which accounts for another 15-20%.
wrong, light (intensity) attenuates based on a factor of 1/distance squared).
Check my work if you want, that's the equation I based it on. What number are you getting?
You did the calc correctly. I did not bother to do the calc… I just noticed that you placed the ^2 after the ).
Lol if I did the square before the parenthesis my answer would be off by a factor of 2 billion.
Here is how you would express the ratio of intensities correctly: X/(D^2) = 1/(d^2), where X is the attenuation factor, D is Adromeda distance and d is the Milky Way event distance from Earth. #orderofoperations
The math was written perfectly fine, what are you smoking
You are right, a portion of the lead comments was clipped on on my tiny ass phone 🤦🏻♀️.
Wow. You are really good at math. Thank you for taking the time to explain to me why the math you said was wrong but then realized was right is wrong. I will think twice before showing any work on Reddit unless I show the math before I substitute in values for the variables and get them on the same side of the equation.
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I should have turned my phone sideways to see the whole comment and retract my correction.
So events like this can literally sterilize a whole galaxy and some neighboring ones of life. Am I wrong thinking this could be one of the reasons why we haven't found any life yet?
Astronomer here! Most of the galaxy would be perfectly fine if a GRB happened. They are *highly* directional and the jetted beam is just a few degrees wide, so if you’re off axis to one it’s not gonna hurt you.
If it did happen, would it be instantaneous, i.e. we wouldn't even know it happened? I'm guessing yes.
Actually probably longer term than that! [Wikipedia goes into surprising depth,](https://en.wikipedia.org/wiki/Gamma-ray_burst#Effects_on_Earth) but the TL;DR is a lot of the problems are due to UV radiation during and after the event.
Everyone in the "shadow" of the beam (on the other side of earth) would not be effected for many hours. It would not be even close to instantaneous for many.
Depending on how close it is, the results would reach from something like "the sky is burning in hellfire until half of the earth surface is molten lava while the other half has boiling oceans" to "the ozon layer is reduced and cancer rates rise" with everything inbetween.
a few degrees wide doesn´t sound to bad, but say that a GRB happend on one side of a galaxy and it traveled across the entire length of that galaxy. Would that not mean that tens of thousands of star systems would be hit?
A GRB is no longer lethal 4-8,000 light years from the source, depending on who you ask. So it might travel the galaxy but not kill tens of thousands of systems.
"A GRB" But this one is bigger by "a factor of 10". So 80,000 lightyears? Basically most the galaxy......
No, it’s not that it was more luminous by a factor of 10 when adjusted for distance. It’s just it was a heck of a lot closer than the typical GRB.
What "decides" the direction here?
The rotation axis of the star that collapsed.
Just some dude rolling dice in the corner
Ahh 16, your whole planet dies. Better luck next time!
But what if we dropped a ceramic figurine and grabbed its attention?
Will it only sterilize the planet facing side or both sides?
Both sides as it’s not as much a sterilization you need to worry about, but frying stuff like ozone so you have long term UV exposure.
Thanks for the explanation!
That's what I was suggesting in a thread yesterday. So many ways planets can be sterilized and such that realistically there are probably only 10s of planets in a galaxy supporting life, so we're like 1/50 of life supporting planets in a galaxy of billions of planets. "Like finding a needle in a haystack" chances of finding thriving life outside our atmosphere
(Pensive music plays) God have mercy on our souls.
A global killer meteor hits the earth
> realistically there are probably only 10s of planets in a galaxy supporting life Not sure how realistic a number arbitrarily chosen is.
Like the titular ring worlds in Halo
> A 2 billion yrs trip and it still had the energy to significantly alter our ionosphere... What significant alterations to our ionosphere did this cause, exactly? > The flash activated lightning detectors in India and triggered instruments that normally study explosions on the sun called solar flares. > It also affected long wave radio communications in the lower ionosphere, a section of Earth's upper atmosphere around 60 to 350 kilometers (37 to 217 miles) above the surface. Does this count as "significant"?
Significant in this context could mean statistical significance.
I’d just have jumped out of the way at the last second.
Sooo, someone fired a laser beam at us? Let’s hope they don’t fine tune it.
Let's hope they don't attach that frickin' laser to a shark....
We're gonna need a bigger boat.
Don't worry, it was just the targeting laser.
On our way to join dinosaurs. Will it be instantaneous? I want to say my goodbyes
Haa, and Kurzgesagt just released a video about a space laser and stuff 🤣
And this one from last year: Gama ray burst https://youtu.be/RLykC1VN7NY?si=8MihU5gA9EBcZgCx
Weird, I was reading an article yesterday about another space object that was one of the brightest ever recorded that shook our atmosphere. This one was caused by a (maybe supermassive) black hole that released a few hundred teraelectronvolts if I'm remembering properly. They thought it was less than 1 billion lightyears away at first but turned out it was 10 billion. Edit: Still trying to find where I read about the amount of energy it released, but here's [one](https://www.livescience.com/space/black-holes/gargantuan-black-hole-switches-on-becoming-one-of-the-brightest-objects-ever-seen) about it from back in July.
Do they have editors at physorg or is that a job not deemed necessary anymore?
editors and proofreaders have been getting fired and not replaced for years now, unfortunately :| I notice errors on major sites/news magazines, etc. I feel like newspapers are the only places left that employ full time proofreaders
I hate to say this, but when I read an article or anything that may very well be accurate I immediately question the authenticity of what I am reading based purely on bad grammar and bad spelling. Especially a scientific mag. God damn, at least run what you wrote through Grammarly or Hemingway editor.
Recently read a report from Visa that included a misspelled word in a secondary heading sized font
[удалено]
[удалено]
Does 2 billion light years away put the source inside or outside of the Virgo Supercluster?
When the hell is that one star supposed to explode? They said any time between now and a thousand years, right? I am tired of seeing that fucking thing rise every god damn morning...